Moldable compositions

ABSTRACT

This invention relates to polymeric thermoplastic moldable compositions comprising poly(alkylene carbonates), which are useful in manufacturing of articles which may be manipulated and shaped by their user, but regain their shape after distortion. These compositions are free from toxic compounds and have a glass transition temperature from about 15° C. to about 132° C. These compositions are useful in manufacturing of articles such as toys, utensils to convey solids or liquids to the mouth, soothing articles (i.e., teething rings and pacifiers) and articles which support food (i.e., candy/confection sticks or holders.) They are most useful in manufacturing of children&#39;s toys and products.

This application is a Continuation of Ser. No. 10/061,776 filed Feb. 1,2002 now U.S. Pat. No. 6,680,359 which is a Continuation of Ser. No.09/469,599 filed Dec. 21, 1999 now abandoned.

This invention relates generally to polymeric thermoplastic moldablecompositions comprising poly(alkylene carbonates) which are useful inmanufacturing articles including, but not limited to articles which maybe manipulated and shaped by their users but regain their shape afterdistortion.

BACKGROUND OF THE INVENTION

Plastics manufactured today for use in articles such as children's toysand products which are placed in the mouth of the user either by designor action of the user pose certain health risks to the user, i.e.,toxicity to the user from the polymers used to manufacture the articleor toxicity from the processing aids used in the manufacturing of thepolymeric article. In addition to the direct health risks to the user ofthese articles, there may be environmental hazards as well.

Polyvinyl chloride (PVC) is a commonly used polymeric material for themanufacture of children's toys and products. Polyvinyl chloride is alsoused in a number of other articles such as toothbrushes, toys, eatingutensils, food storage containers, and dinnerware. Since softness whichis the ability of a compound to bend, yield or become flexible whengentle pressure is applied, (i.e., having a glass transition temperaturefrom about 15° C. or higher) is not an inherent property of PVC as wellas other plastics, and since softness is a desired component for many ofthe articles made from PVC or other plastics, especially articlesintended to be used by children, there is a need to add this property tothe PVC. A common way of addressing this need is to add or employ aprocessing aid in the manufacturing process. Processing aids generallyare added in the manufacturing of polymeric materials to increaseflexibility, workability and extrudablitiy of the end product. In thecase of PVC, processing aids generally referred to as plasticizers andexemplified by a class of compounds known as phthalates are used to addsoftening and flexibility properties to the end product made from PVC.Phthalates are alkyl esters of isomeric benzenedicarboxylic acids.However, these compounds (phthalates) have been linked to liver andkidney damage. Also, it has been reported in the literature that whenused as a processing aid in the preparation of products made of PVC, thephthalates can be leached out of the PVC product. This leaching occurswhen the PVC product containing the phthalates comes in contact withhuman saliva. This situation is of particular concern with products thatare intended for use by children, especially children under the age ofthree.

From an environmental standpoint, the PVCs currently on the market posehealth and environmental hazards when the products are eventuallydestroyed or eliminated through combustion or thermal decomposition.When PVCs are burned, they decompose in to chlorinated chemicals,chlorine and hydrochloric acid, which are toxic. Chlorine andhydrochloric acid are corrosive and the chlorinated compounds are oftenflammable, as well as corrosive, and destructive to the protectivestratosphere which is implicated in global warming and increased cancerhazards due to excessive UV exposure.

Plastics currently on the market, which add potentially toxicplasticizer additives, do not have low glass transition temperaturesallowing for more flexibility and softness as desired when a user ishandling, i.e., softening them from contact with the body caused by bodyheat. These plastics also do not offer abrasion resistance, durability,brilliant coloring and weather resistance in one product.

Therefore, there exists a need in the art for a polymeric material, freeof toxic plasticizers, having softness, flexibility, abrasionresistance, durability, coloring and weather resistance properties, anduseful in the manufacturing of products which may be placed in the moutheither by design or by the action of the user. A need especially existsfor a polymeric material having the aforementioned properties for themanufacturing of products used by children, particularly children underthree years of age.

PRIOR ART DISCUSSION

Harris, U.S. Pat. No. 4,686,273 discloses a process for modifying andincreasing the molecular weight of a poly(alkylene carbonate) polyahl,with at least one modifier having a plurality of moieties that arereactive with the carbonate and/or acting hydrogen moieties of thepoly(alkylene carbonate) polyahl at elevated temperatures and at apressure at which at least one compound other than a monoalkylene glycolwhich compound is at least as volatile as a tetraethylene glycol isremoved in the gaseous state from the poly(alkylene carbonate) polyahl.

Rokicki, U.S. Pat. No. 4,943,677 discloses a process for preparingpoly(alkylene carbonates) of controlled molecular weight bycopolymerizing carbon dioxide and one or more oxirane compounds usingzinc polycarboxylate catalyst in the presence of a sterically hinderedorganic proton donor.

Carroll, et al., U.S. Pat. No. 4,960,862 discloses a process forregenerating metallo-organic catalyst used in copolymerizing carbondioxide with epoxides to form poly(alkylene carbonates).

Maximovich, U.S. Pat. No. 3,896,090 discloses a process for preparingpolycarbonates from an alkylene carbonate and monomeric polyols.

Myers, U.S. Pat. No. 4,686,276 discloses a process for preparingpoly(alkylene carbonate) polymer by the reaction of alkylene oxide withcarbon dioxide and/or an alkylene carbonate at an elevated temperatureand pressure.

Sun, U.S. Pat. No. 4,789,727 discloses a process for preparingpoly(alkylene carbonates) by the reaction of alkylene oxides with carbondioxide in the presence of a catalyst comprising zinc carboxylate and ordiepoxide.

Kuyper, et al., U.S. Pat. No. 4,826,887 discloses a process forpreparing polycarbonates by reacting an epoxy compound with carbondioxide at 40° to 200° C. and 2 to 40 bar in the presence of a catalyst.

Bezwada, et al., U.S. Pat. No. 5,037,950 discloses copolymers comprisingp-dioxanone and poly(alkylene carbonates) useful in fabrication ofsterile surgical articles and bioabsorbable coatings for sutures.

Stevens, U.S. Pat. No. 3,248,415 discloses a process for preparing highmolecular weight polycarbonates from carbon dioxide and 1,2 epoxides.

While the foregoing discloses a number of processes for preparing thepoly(alkylene carbonates) as well as a number of different uses forpoly(alkylene carbonates), there is no art which addresses the use ofthis class of polymers for applicant's invention. Therefore, thereremains a need in the art for this particular application ofpoly(alkylene carbonates).

SUMMARY OF THE INVENTION

The present invention offers a polymeric thermoplastic moldablecomposition comprising polyalkylene carbonates useful in manufacturingof products which may be manipulated and shaped by the user but regaintheir shape after distortion. Accordingly, it is an object of thepresent invention to provide a moldable composition which is non-toxic.It is an object of the present invention to provide a moldablecomposition which has the properties of softness, flexibility, abrasionresistance, durability, coloring and weather resistance, polymericthermoplasticity, elastomeric with recovery and oil resistance. It is afurther object of the present invention to provide products which aremade from the polymeric thermoplastic moldable composition of thepresent invention which are safe when placed in the human mouth andexposed to human saliva. It is a still further object of the presentinvention to provide a method of manufacturing products which may bemanipulated and shaped by the user but will regain their shape afterdistortion wherein the method is safe and cost-effective. It is a stillfurther object of the present invention to provide a polymericthermoplastic moldable composition which is useful in the manufacturingof articles intended for use by children especially, but not limited tochildren under the age of three.

Definition of Terms

The term “manipulated and shaped by the user” is defined as thedistortion of the article from its intended, original molded shape bythe user of the article. For example, a straw which is molded to bestraight can be bent by the user; a teething ring or pacifier can becompressed by the user's teeth or gums; the handle portion of utensilsdesigned to convey food to the mouth can be bent from its originalposition.

The term “toy” is defined as an article designed to amuse the user;these types of articles are usually intended to be used by children.Toys can be exemplified by, but not limited, to solid or hollow balls,sphericals, footballs, baseballs, puzzles, blocks, saucers and disksintended for throwing, dolls and figurines.

The term “soothing article” is defined as an article intended to ease ormitigate pain to some degree. These articles can be exemplified byteething rings and pacifiers.

The term “utensils for the purposes of conveying solids or liquids tothe mouth” is meant to include, but not limited to, spoons, forks,knives, baby bottle nipples, straws, sipping cup lids and cups.

The term “articles which support food” is meant to include, but not belimited to, candy/confection sticks or holders, frozen novelty holders(i.e., ice cream/ice pops).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a moldable composition comprisingpoly(alkylene carbonates) which are useful in manufacturing of articleswhich may be manipulated and shaped by their users, but regain theirshape after distortion. The articles which are made from thepoly(alkylene carbonate) compositions may be molded into any desiredshape and form. The compositions may also be molded into a solid, walledarticle in which a liquid (i.e., water) may be contained. Thepoly(alkylene carbonates) of the present invention have a glasstransition temperature ranging from about 15° C. to about 132° C.

Articles which are suitable for the practice of this invention are toyswhich are created for the amusement of the user especially children;i.e., solid or hollow balls, sphericals, footballs, baseballs, puzzles,blocks, saucers and disks intended for throwing, dolls and figurines,utensils for the purpose of conveying food or liquids to the mouth(i.e., straws, spoons); articles which may be placed in the mouth forsoothing purposes (i.e., teething rings and pacifiers) and articleswhich support food (i.e., candy/confection sticks or holders).

The properties of poly(alkylene carbonates) allow for safe, durable andcreative usage. Because of the low glass transition temperature(preferably from about 15° C. to about 40° C.) of certain poly(alkylenecarbonates), products held in a hand or used in the mouth become moresoft and flexible. In products including, but not limited to, feedingutensils, toothbrushes, straws and sticks or holders forcandy/confections, there would be less potential for injury to the childif they should fall with the product. The flexibility of the plasticwould allow for compression when pressure is applied to productsincluding, but not limited to, teething rings and pacifiers. Whenpressure is removed, the object will recover to its original shape. Initems including, but not limited to, teething rings, pacifiers,toothbrushes, sipping cup lids, feeding utensils and bottle nipples, theabrasion resistant property would minimize teethmark wear and thepotential for the user to extract plastic particles from the product.Additionally, poly(alkylene carbonates) are weather resistant and wouldretain color and durability when used for, but not limited to, furnitureand toys that are intended for outdoor use. Finally, the clear propertyof poly(alkylene carbonates) gives products the ability to color morebrilliantly, or to remain clear.

Poly(alkylene carbonates), also known as CO₂ copolymers are straight,chains of repeating units of molecules resulting from the reaction ofolefinically saturated aliphatic 1,2 epoxides with carbon dioxide.

Olefinically saturated aliphatic compounds which are suitable for use inthe syntheses of poly(alkylene carbonates) are exemplified by ethylene,propylene, butylene and pentene. A complete discussion on the synthesisfor poly(alkylene carbonates) can be found in U.S. Pat. No. 4,943,677which is hereby incorporated by reference.

Poly(alkylene carbonates) have many unique characteristics includingsome of which are, but not limited to, lubricity, low glass transitiontemperature, clean products from combustion (primarily carbon dioxideand water), abrasion resistance, weather resistance, clear coloration,and oil resistance. The elastomeric polymers of this class of polymers,poly(ethylene carbonates) and poly(butene carbonate), which can bestretched, are polymeric thermoplastic, oil resistant, have a highdegree of recovery, and a low glass transition temperature, areparticularly useful in the practice of this invention.

Depending on the specific properties desired for the molded article thecomposition may contain a single poly(ethylene carbonate) or a blend oftwo or more poly(alkylene carbonates).

The use of poly(ethylene carbonates) or poly(butene carbonates), forinstance, used singly in a composition would produce a molded articlehaving softness and flexibility at relatively low temperatures from bodyheat. The use of poly(cyclohexene carbonate) having a glass transitiontemperature of 132° C. would produce a molded article having morerigidity. It will be apparent to those skilled in the art, however, thatadditional material other than the poly(alkylene carbonates), may beadded to the composition to aid in manufacturing or add additionalproperties to the composition.

There are many different molding/forming processes for molding articlesof the present invention. These processes can be exemplified by coating,swaging, shaping, die-pressing, laminating, extruding and molding,including injection molding.

Poly(alkylene carbonates) are normally polymeric thermoplastic polymers.Polymeric thermoplastic polymers soften on heating and harden whencooled and can be re-softened by reheating. Poly(alkylene carbonates)can be made thermosetting by appropriate cross-linking. Thermosettingpolymers soften on heating but harden by continuous exposure to heat andsubsequently cannot be softened thereafter by heating again.

Poly(alkylene carbonates) can be made with a wide range of properties.These properties can range from soft elastomeric polymers to hardengineering, rigid type polymers, based on the epoxide used to reactwith carbon dioxide, e.g., they can have glass transition temperatures,i.e., softening points that range from about 15° C. to about 132° C.Poly(alkylene carbonates) can also have the following propertiesdepending on the particular epoxide used in the process:

-   -   Biodegradable (i.e., poly(ethylene carbonates))    -   Enzyme degradable (i.e., poly(ethylene carbonates))    -   Elastomeric with high recovery from deformation (i.e.,        (poly(ethylene carbonates), poly(butene carbonates))    -   Clear and amorphous    -   Durable and printable    -   Abrasion resistant (i.e., (polyethylene carbonates))    -   Low glass transition temperatures (i.e., poly(ethylene        carbonates)) about 25° C.; poly(propylene carbonates) about 40°        C.; poly(butene carbonates) about 15° C.)    -   Processed easily with conventional equipment, e.g., molding,        extrusion, etc.    -   Coloring brilliance    -   Excellent adhesion to paper    -   Recyclable    -   Oil barrier (i.e., poly(ethylene carbonates), poly(butene        carbonates))    -   Oxygen barrier

Example for Molding an Article of the Present Invention

Injection molding using poly(ethylene carbonate) and poly(propylenecarbonate) to form a molded article according to the invention is asfollows:

Machine:

-   -   1. Injection molding machine with three-zone heating in the        barrel    -   2. One inch diameter screw    -   3. Length to diameter ratio of 20 to 1    -   4. Pellet, granular or powder, feed

Conditions Temperature ° C. Preferred ° C. Nozzle 130-190 160-185 Frontzone 130-190 160-185 Middle zone 150-180 160-175 Rear zone 110-150130-145 Cycle Times Overall cycle time 50-70 seconds Overall injectiontime 12-18 seconds Initial injection time 6-12 seconds Initial injectionpressure 500-700 pounds per square foot Secondary injection pressure200-400 pounds per square foot Screw speed 20-30 rpm

Throat must be cold.

Mold must be chilled (dry ice)

Process conditions will be affected by the polymer molecular weightdistribution.

Blends of poly(ethylene carbonate) and poly(propylene carbonate) can bemade to obtain properties in between those of the two polymers, if thisis desirable, e.g., a blend of elastomeric poly(ethylene carbonate) andmore rigid, non-elastomeric poly(propylene carbonate) would giveproperties between the two on rigidity/elasticity.

Poly(ethylene carbonates) having a glass transition temperature betweenabout 20° C. to about 25° C. and having the properties of softening,flexibility, polymeric thermoplasticity, elastomeric, oil and oxygenbarrier are useful in the compositions of the present invention.

1. A molded article for use by a child capable of being manipulated anddistorted from its original shape when placed in the mouth of a childand exposed to the child's saliva but capable of regaining its originalshape after distortion wherein said molded article comprises apoly(alkylene carbonate) having a glass transition temperature fromabout 15° C. to about 40° C. wherein said poly(alkylene carbonate)comprises a blend of two or more poly(alkylene carbonates) wherein thepoly(alkylene carbonates) are selected from the group consisting ofpoly(ethylene carbonates), poly(butene carbonate) and poly(propylenecarbonates), and wherein said molded article is free from toxicplasticizers or softening aids.
 2. The molded article according to claim1 wherein said molded article is selected from the group consisting ofchildren's toys, soothing articles, feeding implements and articleswhich support food.
 3. The molded article according to claim 2 whereinthe toys are selected from the group consisting of solid or hollowballs, sphericals, footballs, baseballs, puzzles, blocks, saucers anddisks intended for throwing, dolls and figurines.
 4. The molded articleaccording to claim 2 wherein the soothing articles are selected fromteething rings and pacifiers.
 5. The molded article according to claim 2wherein the feeding implements are selected from the group consisting ofchildren's spoons, forks, knives, bottle nipples, straws, sipping cuplids and cups.
 6. The molded article according to claim 2 wherein thearticles which support food are selected from candy and confectionsticks and frozen novelty holders.